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AGRICULTURE 


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UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


BULLETIN  NO.  283 


A  TECHNICAL  STUDY  OF  THE 

MAINTENANCE  AND  FATTENING  OF 

SHEEP  AND  THEIR  UTILIZATION 

OF  ALFALFA  HAY 


BY  H.  H.  MITCHELL,  W.  G.  KAMMLADE, 
AND  T.  S.  HAMILTON 


URBANA,  ILLINOIS,  DECEMBER,  1926 


WHILE  the  methods  of  study  and  the  results  secured  in  this  in- 
vestigation are  mainly  of  a  technical  nature,  the  sheep  raiser  will 
be  directly  interested  in  several  of  the  facts  established: 

1.  The  feeding  of  alfalfa  hay  alone  was  continued  for  133  days 
with  six  sheep  and  308  days  with  six  others,  with  no  apparent  indica- 
tions of  harmful  effects. 

2.  Sixteen  percent  of  the  gain  in  live  weight  was  due  to  "fill." 

3.  A  comparison  of  the  results  secured  in  this  investigation  with 
the  results  secured  in  investigations  with  steers  indicates  that  these 
two  species  of  animals  are  about  equal  in  their  ability  to  utilize  the 
metabolizable  (or  available)  energy  of  alfalfa  hay  in  fattening. 

4.  Approximately  2.3  pounds  of  alfalfa  hay  per  day  per   100 
pounds  of  live  weight  maintained  ten-  to  fourteen-months-old  western 
lambs  at  constant  weight  for  133  days.    Amounts  greater  than  this 
must  be  fed  to  allow  for  growth  and  fattening. 

5.  The  daily  growth  of  wool  during  the  fattening  period  contained 
only  .015  of  a  pound  of  protein  for  a  sheep  weighing  100  pounds. 

6.  In  the  total  increase  in  "empty"  weight  during  fattening  60 
percent  of  the  dry  matter,  34  percent  of  the  protein,  73  percent  of  the 
fat,  47  percent  of  the  mineral  matter,  and  66  percent  of  the  gross  en- 
ergy were  added  to  the  dressed  carcass,  mainly  to  the  boneless  meat. 
The  wool  grown  contained  23  percent  of  the  dry  matter,  60  percent  of 
the  protein,  52  percent  of  the  mineral  matter,  6  percent  of  the  fat,  and 
14  percent  of  the  gross  energy  contained  in  the  added  weight. 


A  TECHNICAL  STUDY  OF  THE 

MAINTENANCE  AND  FATTENING  OF 

SHEEP  AND  THEIR  UTILIZATION 

OF  ALFALFA  HAY 

BY  H.  H.  MITCHELL,  W.  G.  KAMMLADE,  and  T.  S.  HAMILTON1 

Precise  information  concerning  the  nutritive  requirements  of  sheep 
for  either  maintenance  or  fattening  is  difficult  to  find  in  the  literature. 
In  his  book,  "The  Nutrition  of  Farm  Animals,"  Armsby  quotes  a  few 
experiments  bearing  on  the  maintenance  requirement  of  sheep,  most 
of  which,  however,  were  not  so  planned  as  to  give  the  informa- 
tion desired  by  direct  calculation. 

Slaughter  results  on  sheep,  from  which  the  composition  of  gains 
in  weight  may  be  computed,  are  also  few  in  number.  The  only  com- 
plete analyses  of  the  entire  carcasses  of  sheep  in  different  stages  of 
fattening  seem  to  be  those  of  Lawes  and  Gilbert2  published  in 
1859.  Partial  analyses  of  carcasses  of  sheep  have  been  reported 
by  other  investigators,  but  such  results  cannot  be  used  in  the  com- 
putation of  the  composition  of  gains  in  weight  without  the  use  of 
assumed  values  for  the  composition  of  the  unanalyzed  parts.  Further- 
more, the  question  of  the  utilization  of  feed  energy  by  fatten- 
ing sheep  has  been  practically  untouched  except  for  a  few  computa- 
tions by  Armsby3  based  upon  the  results  of  a  series  of  respiration  ex- 
periments upon  two  sheep  by  Kern  and  Wattenberg.  The  usual  as- 
sumption that  Armsby 's  net  energy  values  of  feeds  apply  to  sheep  as 
well  as  to  cattle  seems  to  rest  entirely  upon  these  few  computations. 

It  was  the  purpose  of  the  experiment  reported  in  this  bulletin  to 
throw  some  light  upon  these  questions  relating  to  the  nutrition  of 
sheep. 

OUTLINE  OF  THE  EXPERIMENT 

To  simplify  the  calculations  of  the  experiment  and  to  give  the  re- 
sults a  more  definite  significance,  the  ration  used  thruout  the  experi- 
ment was  alfalfa  hay  alone. 


*H.  H.  MITCHELL,  Chief  in  Animal  Nutrition;  W.  G.  KAMMLADE,  Assistant 
Chief  in  Sheep  Husbandry;  T.  S.  HAMILTON,  Associate  in  Animal  Nutrition. 

"Armsby,  H.  P.  The  Nutrition  of  Farm  Animals,  653.   1917. 

'Armsby,  H.  P.,  and  Moulton,  C.  R.  The  Animal  as  a  Converter  of  Matter 
and  Energy,  42.  1925. 

223 


224  BULLETIN  No.  283  [December, 

Twelve  western  lambs,  about  ten  months  of  age  at  the  beginning 
of  the  experiment,  were  placed  upon  a  maintenance  allowance  of  al- 
falfa hay  on  February  15,  1923.  The  sheep  weighed  close  to  100  pounds 
per  head,  the  variation  in  weight  ranging  from  90.5  to  104  pounds. 
Each  sheep  was  fed  individually  and  allowed  2  pounds  of  alfalfa  hay 
daily  regardless  of  its  weight.  After  a  preliminary  period  of  three 
weeks,  during  which  time  the  body  weight  became  adjusted  to  the  food 
intake,  the  maintenance  experiment  was  considered  to  have  started. 
In  the  course  of -this  experiment,  which  lasted  126  days,  each  sheep 
was  subjected  to  a  digestion  and  metabolism  test  of  7  days'  duration, 
to  determine  the  intake  of  digestible  nutrients  and  metabolizable  en- 
ergy. The  feed  records  of  this  period,  together  with  the  results  of  the 
metabolism  studies,  permit  a  computation  of  the  amount  of  metabol- 
izable energy  in  alfalfa  hay  required  for  the  maintenance  of  sheep. 

At  the  end  of  the  maintenance  period  6  of  the  12  sheep  were 
slaughtered  and  their  entire  carcasses  analyzed  to  determine  the  con- 
tent of  nutrients  and  gross  energy.  The  remaining  6  sheep  were  put 
upon  increased  amounts  of  alfalfa  hay,  permitting  a  certain  amount 
of  fattening.  During  this  fattening  period  each  of  the  sheep  was  again 
subjected  to  a  digestion  and  metabolism  trial  of  10  days'  duration,  and 
at  the  end  of  182  days,  during  which  the  sheep  gained  from  18  to  42 
pounds  in  wreight,  they  were  slaughtered  and  analyzed. 

The  results  of  the  analysis  of  the  fat  sheep,  compared  with  the  re- 
sults of  the  analysis  of  the  maintenance  sheep,  permit  a  calculation  of 
the  composition  of  the  gains.  The  energy,  protein,  and  ash  content  of 
these  gains  is  a  fair  measure  of  the  energy,  protein,  and  ash  required  to 
produce  them.  The  feed  records  of  the  fattening  period,  in  comparison 
with  the  feed  records  of  the  maintenance  period,  permit  a  computation 
of  the  amount  of  alfalfa  hay  consumed  during  the  fattening  period 
above  the  maintenance  requirement.  The  metabolism  studies  permit 
the  computation,  from  these  feed  records,  of  the  metabolizable  energy 
required  for  maintenance  and,  in  the  fattening  experiment,  the  con- 
sumption of  metabolizable  energy  above  the  maintenance  require- 
ments. A  comparison  of  these  results  with  the  gross  energy  of  the 
gains  secured  permit  the  computation  of  the  net  availability  of  the 
metabolizable  energy  of  alfalfa  hay  for  fattening. 

The  alfalfa  hay  was  sampled  each  day  thruout  the  feeding  tests, 
and  was  analyzed  at  somewhat  irregular  intervals,  with  the  results 
showrn  in  Table  1. 

THE  MAINTENANCE  EXPERIMENT 

The  pen  in  which  the  lambs  were  allowed  to  exercise  was  approx- 
imately 1  by  5  rods.  Water  and  salt  were  provided  ad  libitum.  Each 
lamb  was  fed  in  an  individual  section  of  a  feed  rack  located  in  a  shed 
open  toward  the  south.  The  lambs  wore  straps  about  their  necks,  to 


FEED  REQUIREMENTS  OF  SHEEP 


225 


which  were  attached  number  tags  for  identification  and  iron  rings; 
the  rings  were  used  in  tying  the  lambs  in  their  proper  section  of  the 
feed  rack.  Except  at  feeding  time,  the  lambs  were  allowed  the  run  of 
the  open  pen. 

The  period  during  which  the  body  weights  of  the  sheep  were  main- 
tained at  approximately  constant  level  on  constant  feed  consumption 

TABLE  1. — CHEMICAL  COMPOSITION  OF  THE  ALFALFA  HAY  USED 
THRUOUT  THE  EXPERIMENTS 


Dry 

Crude 

N-free 

Ether 

Gross 

Dates 

sub- 

pro- 

ex- 

ex- 

Ash 

Crude 

energy 

stance 

tein 

tract 

tract 

fiber 

per 

gram 

perct. 

perct. 

perct. 

perct. 

perct. 

perct. 

small 
cols. 

Mar.  2-May  31  

92  18 

15  38 

39  51 

1.64 

6.60 

29.05 

4  126 

May  31-Julv  16  

91  71 

14  42 

41  40 

1  81 

6.44 

27.64 

3  978 

July  16-Sept.  10  

92.89 

17.56 

38.07 

2.24 

6.81 

28.21 

4  192 

Sept.  10-Oct.  9  

93.43 

17  02 

42.38 

2.27 

8.91 

22.85 

4  125 

Oct.  9-Nov.  12  

94  41 

14.84 

41  72 

2  04 

7.40 

28.41 

4  112 

Nov.  12-Jan.  7  

93.33 

15.50 

37.83 

1.64 

6.88 

31.48 

4  161 

Average    for    mainten- 

ance experiment  

92.0 

15.1 

40  1 

1.7 

6.5 

28.6 

4  077 

Average   for   fattening 

experiment  

93.4 

16.3 

39.4 

2.0 

7.3 

28.4 

4  155 

lasted  from  March  5  to  July  9,  a  total  of  126  days.  On  July  9  six  of 
the  sheep  were  placed  upon  increased  amounts  of  alfalfa  hay.  How- 
ever, since  it  was  not  convenient  to  slaughter  the  remaining  6  animals 
on  this  date,  they  were  held  over  for  a  week  on  the  same  intake  of  feed, 
so  that  the  maintenance  trial  with  these  sheep  lasted  for  133  days. 

The  weekly  weights  of  the  12  sheep  in  the  maintenance  experi- 
ment are  given  in  Table  2.  The  interpretation  of  these  results  is  some- 
what complicated  by  the  fact  that  it  was  found  necessary  on  May  1, 
when  the  maintenance  trial  was  only  about  half  complete,  to  shear  the 
sheep,  because  of  the  increasingly  warm  weather.  Tho  the  body 
weights  were  thus  reduced  by  amounts  varying  from  4  to  9  pounds, 
there  seemed  to  be  no  tendency  for  the  sheared  sheep  to  increase  in 
weight  on  the  same  amount  of  feed.  The  blank  spaces  in  the  table 
represent  those  periods  during  which  the  sheep  were  in  the  metabolism 
crates. 

The  metabolism  periods  were  of  7  days'  duration,  the  sheep  being 
handled  in  groups  of  three,  since  only  three  metabolism  crates  were 
available.  The  crates  used  were  modeled  after  those  which  E.  B. 
Forbes  used  in  his  numerous  nutrition  experiments  on  swine.  In  ap- 
plying these  crates  to  metabolism  work  on  sheep,  it  was  found  advis- 
able to  increase  the  size  of  the  windows  and  to  put  a  window  on  each 
side  of  the  crate,  so  that  the  sheep  could  see  each  other  during  the  trial. 


226 


BULLETIN  No.  283 


[December, 


TABLE   2. — WEEKLY   WEIGHTS   OP   SHEEP   DURING   MAINTENANCE   EXPERIMENT 

(All  weights  in  pounds) 


Sheep  No.  .  . 

142 

143 

144 

145 

146 

147 

148 

149 

150 

151 

152 

153 

1923 
Mar.  5  

98 

9?! 

92 

95 

101 

99 

89 

97 

91 

92 

91 

95 

Mar.  12.... 
Mar.  19.... 
Mar.  26.... 

Apr.  2  

96 

98 
97 

96 

91 
92 
94 

94 

92 
92 
94 

93 

97 
98 
99 

96 

101 
100 
101 

103 

96 
97 

98 

101 

89 
89 
90 

91 

96 
97 
99 

98 

90 
91 
92 

93 

90 
93 
94 

93 

90 
92 
94 

94 

94 
93 

94 

93 

Apr.  9  

96 

94 

91 

96 

99 

99 

88 

97 

92 

94 

92 

94 

Apr.  16  
Apr.  23  

May  I1  
May  7  

102 
97 

96 

97 
95 

86 

95 
95 

89 

10(f 
98 

95 
94 

104 
102 

93 
92 

102 
100 

95 
93 

93 

92 

88 
85 

104 
101 

94 
92 

97 
95 

88 
87 

97 

96 

89 
88 

97 

97 

97 
89 

95 
95 

97 
89 

May  14.  .  .  . 
May  21  

92 
89 

84 
81 

86 
83 

'86 

'85 

'87 

86 

93 

87 

89 

85 

90 

87 

87 

87 

May  28.  ..  . 
June  4  

93 
91 

85 
82 

88 
84 

93 
90 

90 

86 

92 

88 

88 
83 

89 

88 

87 
83 

June  11.  .  .  . 
June  18  
June  25  .... 

July  2  
July  9  
July  16.  .  .  . 

88 
93 
98 

87 
91 

85 

81 
83 

87 

78 
83 

8? 

83 
84 
88 

82 
84 

86 
90 
94 

87 
90 

87 
87 
91 

84 
88 
82 

89 
91 
93 

89 
91 

80 
83 
84 

79 
81 
76 

89 
89 
93 

87 
88 

83 
83 

88 

80 
83 

78 

84 
85 
86 

81 
84 

78 

86 
86 
89 

84 
85 

84 

86 
87 

83 

85 

Fleece 
weights.  . 

6.5 

7.0 

6.0 

4.0 

9.0 

7.5 

6.5 

7.0 

7.25 

7.0 

7.0 

7.0 

*A11  sheep  were  sheared  on  May  1,  except  the  last  three,  which  were  sheared  on 
May  7.  The  weights  on  the  date  of  shearing  and  on  all  subsequent  dates  are  ex- 
clusive of  the  weights  of  the  fleece  removed. 


TABLE  3. — COEFFICIENTS  OF  DIGESTIBILITY  OF  ALFALFA  HAY  FED  AS  A 
MAINTENANCE  RATION 


Sheep  No. 

Dry 

substance 

Crude 
protein 

N-free 
extract 

Ether 
extract 

Crude 
fiber 

142.  . 

perct. 
55.6 

perct. 
67.4 

perct. 
72  A 

perct. 
8.6 

perct. 
20.0 

143  

58.7 

68.2 

75.1 

9.2 

26.7 

144  

57.3 

67.5 

70.9 

7.2 

30.3 

145.  . 

55.7 

68.9 

68.5 

12.0 

30.8 

146  

58.2 

68.3 

71.7 

27.4 

34.1 

147  

59.5 

68.4 

72.7 

26.4 

36.5 

148    

53.2 

64.5 

70.7 

41.1 

19.3 

149  

57.2 

68.0 

71.9 

34.3 

28.7 

150  

54.8 

65.3 

69.1 

45.5 

25.7 

151  

51.8 

67.9 

69.0 

13.0 

20.2 

152  

53.3 

67.0 

70.9 

3.0 

22.5 

153  

51.8 

66.4 

69.6 

0.0 

20.3 

Average  

55.6 

67.3 

71.0 

19.0 

26.3 

1926'}  FEED  REQUIREMENTS  OF  SHEEP  227 

Under  these  conditions  they  were  much  more  tractable.  Another  mod- 
ification of  the  Forbes  crate  was  the  substitution  of  a  copper  wire 
screen  of  fine  mesh  for  the  cloth  used  by  Forbes  to  retain  the  feces. 
This  screen  seemed  to  be  much  more  easily  washed  in  the  small  vol- 
umes of  water  advisable  for  this  work  than  was  the  cloth  originally  rec- 
ommended. Altho  these  copper  screens  will  tarnish  in  time,  there  is  no 
reason  for  believing  that  the  composition  of  the  urine  draining  thru 
them  is  appreciably  changed.  During  the  metabolism  test  the  sheep  re- 
ceived the  same  amount  of  alfalfa  hay  as  they  had  been  consuming  for 
a  number  of  weeks  and  the  alfalfa  hay  was  approximately  of  the  same 
quality. 

The  detailed  results  of  the  digestion  and  metabolism  experiments 
are  given  in  the  Appendix.  A  summary  of  the  coefficients  of  digesti- 
bility computed  in  the  ordinary  fashion  is  given  in  Table  3.  The  in- 
dividual coefficients  are  fairly  constant  among  themselves  with  the  ex- 
ception of  the  coefficients  for  crude  fat  (ether  extract).  The  small 
amount  of  ether  extract  in  alfalfa  hay  and  the  large  amount  in  the  in- 
testinal secretions  renders  an  accurate  estimate  of  the  digestibility  of 
the  ether  extract  of  alfalfa  hay  difficult,  if  not  impossible.  There  was 
no  refused  feed  in  any  of  these  digestion  trials. 

An  estimate  of  the  metabolizable  energy  of  the  alfalfa  hay  was 
rendered  possible  by  the  fact  that  the  urine,  as  well  as  the  feces,  was 
^collected,  and  that  the  energy  content  of  feed  and  excreta  was  directly 
determined  in  the  bomb  calorimeter.  The  nitrogen  content  of  the  urine 
was  also  determined  for  the  purpose  of  obtaining  a  determination  of 
the  nitrogen  balances.  By  means  of  the  nitrogen  balance  the  metabol- 
izable energy  of  the  hay  can  be  corrected  for  protein  stored  in  the 
body  or  protein  catabolized  from  the  body.1  In  Table  4  the  various 
stages  in  the  computation  of  the  metabolizable  energy  of  the  alfalfa 
hay  are  given. 

The  methane  output  of  the  sheep  was  computed  from  the  amount 
of  digestible  carbohydrates  consumed,  Armsby's  factor  of  4.5  grams  of 
methane  per  100  grams  of  digestible  carbohydrates  being  used.  From 
this  table  it  will  be  seen  that  the  average  percentage  of  the  gross  en- 
ergy of  the  alfalfa  hay  that  was  metabolizable  was  42.9,  a  figure  agree- 
ing closely  with  that  obtained  by  Armsby  in  experiments  on  steers,  ref- 
erence to  which  will  be  made  later.  The  metabolizable  energy  was 
computed  to  be  1.69  therms  per  pound  of  digestible  organic  matter,  a 
figure  somewhat  larger  than  the  average  figure  Armsby  gives  for 
roughages,  namely,  1.588  therms. 

During  the  maintenance  experiment  only  small  amounts  of  feed 
were  refused,  less  than  2  percent  of  the  feed  offered  in  all  cases.  The 
refused  feed  consisted  mainly  of  small  pieces  of  stem,  but  on  account 


1Armsby,  H.  P.,  and  Fries,  J.  A.   U.  S.  Dept.  of  Agr.  Bur.  of  Anira.  Indus., 
Bui.  101,  31.    1908. 


228 


BULLETIN  No.  283 


[December, 


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229 


of  the  small  amount  of  such  refused  feed  thruout  the  test,  the  compo- 
sition of  the  feed  consumed  was  practically  the  same  as  the  average 
composition  of  the  alfalfa  hay  offered. 

A  summary  of  the  more  important  results  of  the  experiment  rel- 
ative to  the  feed  requirements  for  maintenance  are  given  in  Table  5. 


TABLE  5. — AVERAGE  RESULTS  OF  THE  MAINTENANCE  EXPERIMENT 

Data  for  sheep  slaughtered  at  end  of  experiment 


Sheep  No  

142 

143 

146 

148 

150 

151 

Days  on  experiment  

133 

133 

133 

133 

133 

133 

Average  live  weight  

Ibs. 
90  8 

to*. 
82.7 

Ibs. 
86.8 

Ibs. 
82.6 

Ibs. 
84.0 

Ibs. 
84.6 

Total  feed  offered  

266.0 

266.0 

267.4 

266.0 

266.0 

266.0 

Total  feed  refused  

5.9 

3.7 

5.0 

3.8 

1.4 

3.4 

Total  feed  consumed  

260.1 

262.3 

262.4 

262.2 

264.6 

262.6 

Average  daily  feed  consumed  

1.96 

1.97 

1.97 

1.97 

1.98 

1.97 

Feed  consumed  per  day  per  100  pounds 
live  weight: 
Computed  by  weight  ratio  

2  16 

2  38 

2.27 

2  38 

2  36 

2.30 

Computed  by  surface  ratio  

2.10 

2.24 

2.16 

2.24 

2.22 

2.23 

Metabolizable   energy   per   day   per    100 
pounds  weight 

Computed  by  weight  ratio  

cals. 
1  697 

cals. 
2  007 

cals. 
1  914 

cals. 
1  862 

cals. 
1  959 

cals. 
1  772 

Computed  by  surface  ratio  

1  650 

I  888 

1  821 

1  752 

1  843 

1  671 

Data  for  sheep  fattened  at  end  of  experiment 


Average 

Sheep  No  

144 

145 

147 

149 

152 

153 

of  12 

sheep 

Days  on  experiment  

126 

126 

126 

126 

126 

126 

Ibs. 

Ibs. 

Ibs. 

Ibs. 

Ibs. 

Ibs. 

Ibs. 

Average  live  weight  

84  7 

89  3 

90  0 

89  4 

86  4 

85  4 

Total  feed  offered  

252.0 

252.0 

254.8 

252  0 

252.0 

252.0 

Total  feed  refused  

1.0 

0.0 

.6 

.5 

3.3 

2.4 

Total  feed  consumed  

251  0 

252  0 

254  2 

251  5 

247  8 

249  6 

Average  daily  feed  consumed  

1.99 

2.00 

2.02 

1  99 

1.97 

1.98 

Feed  consumed  per  day  per  100 

pounds  live  weight 

Computed  by  weight  ratio  

2.35 

2.24 

2.24 

2.23 

2.28 

2.32 

2.295 

Computed  by  surface  ratio  .... 

2.22 

2.16 

2.17 

2.14 

2.17 

2.20 

2.185 

Metabolizable   energy   per   day 

per  100  pounds  weight 

cals. 

cals. 

cals. 

cals. 

cals. 

mix. 

cals. 

Computed  by  weight  ratio.  .  .  . 

1  925 

1  735 

1  806 

I  798 

1  665 

1  707 

1  820 

Computed  by  surface  ratio.  .  .  . 

1  819 

1  673 

1  749 

1  725 

1  585 

1  619 

1  733 

The  final  requirements  have  been  expressed  in  terms  of  feed  consumed 
and  metabolizable  energy  used  per  100  pounds  live  weight,  and  have 
been  computed  from  the  actual  experimental  results  both  by  the  simple 
weight  ratio  and  by  the  surface  ratio,  that  is,  the  ratio  of  the  two- 
thirds  power  of  the  body  weight.  Since  the  average  weight  of  the 
sheep  was  fairly  close  to  100  pounds  in  all  cases,  the  results  of  the  two 
methods  of  computation  are  closely  similar.  The  amount  of  alfalfa 


230 


BULLETIN  No.  283 


[December, 


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1926]  FEED  REQUIREMENTS  OF  SHEEP  231 

hay  required  per  day  per  100  pounds  live  weight,  by  the  12  sheep,  av- 
eraged 2.295  pounds  computed  by  the  weight  ratio,  and  2.185  pounds 
computed  by  the  surface  ratio.  The  individual  variations  from  the 
average  figures  were  very  slight.  From  the  individual  figures  relative 
to  the  amount  of  alfalfa  hay  required  for  100  pounds  live  weight,  from 
the  average  gross  energy  value  of  the  alfalfa  hay  fed  thruout  the  test, 
and  from  the  individual  percentages  of  the  gross  energy  which  were 
computed  to  have  been  metabolized  by  the  individual  sheep,  individual 
values  for  the  metabolizable  energy  required  per  day  per  100  pounds 
live  weight  were  obtained.  These  values  averaged  1,820  calories  com- 
puted by  the  weight  ratio,  and  1,733  calories  computed  by  the  surface 
ratio. 

From  several  live-weight  experiments  on  sheep,  Armsby1  com- 
putes their  metabolizable  energy  requirement  for  maintenance  to  be 
1,624  calories,  a  figure  closely  approximating  our  average  of  1,733  cal- 
ories computed  in  the  same  fashion.  The  figures  from  these  live-weight 
experiments  average  distinctly  higher  (23  percent)  than  similar  re- 
sults computed  from  respiration  experiments,  probably  because  of  a 
greater  degree  of  muscular  activity  in  the  experimental  animals.  The 
computed  requirements  of  this  experiment,  and  of  other  live-weight  ex- 
periments, obviously  refer  to  what  Armsby  has  called  "economic  main- 
tenance," rather  than  to  "physiological  maintenance,"  the  latter  term 
representing  a  condition  of  absolute  quiet. 

A  summary  of  the  most  important  slaughter  data  on  the  6  sheep 
that  were  killed  at  the  end  of  the  maintenance  trial  will  be  found  in 
Table  6.  The  average  dressing  percentage  of  these  sheep,  on  the  basis 
of  the  chilled  carcasses,  was  47.23,  which  is  appreciably  below  the  av- 
erage for  sheep  in  market  condition.  The  shrinkage  averaged  2.85 
percent,  while  the  cold  dressed  carcasses  contained  an  average  of  75 
percent  of  boneless  meat.  The  contents  of  the  alimentary  tract  aver- 
aged 16.7  percent  of  the  live  weight,  varying  from  14.1  to  22.0  percent. 
The  sheep  were  killed  on  the  morning  of  July  16  and  had  received  their 
last  feed  at  about  10  a.  m.  on  the  preceding  day. 

The  chemical  analysis  of  the  carcasses  of  the  sheep  was  made  upon 
two  individual  samples, — a  composite  sample  of  the  dressed  carcass, 
and  an  offal  sample, — and  upon  two  composite  samples  for  the  entire 
group,  namely,  the  hide  and  the  wool.  In  preparing  the  carcass  compos- 
ite sample,  the  dressed  carcass  was  cut  up  by  the  butcher  into  bones 
and  boneless  meat,  the  separation  being  as  complete  as  could  be  made 
readily  with  a  knife.  These  two  fractions  of  the  carcass  were  weighed 
separately  and  ground  finely  in  a  power  sausage  mill.  They  were  then 
mixed  separately,  quartered  down,  and  a  convenient  composite  sample 
made  by  combining  the  ground  bone  and  ground  meat  in  the  same  pro- 
portion by  weight  in  which  they  occurred  in  the  carcass.  The  offal 

lrThe  Nutrition  of  Farm  Animals,  294.    1917. 


232 


BULLETIN  No.  283 


[December, 


sample  contained  the  blood,  head,  feet,  and  the  viscera  with  the  excep- 
tion of  the  kidneys,  the  latter  being  included  in  the  carcass  composite 
sample.  After  putting  the  head  and  feet  thru  a  bone  grinder,  they 
were  ground  with  the  soft  tissues  in  the  offal  sample  and  intimately 
mixed.  The  fresh  pelts  were  weighed  as  soon  as  removed  from  the 
carcass  and  the  inner  surfaces  were  painted  with  a  concentrated  solu- 
tion of  a  sulfid  depilatory.  The  following  morning  the  wool  was  pulled 

TABLE  7. — PEBCENTAGE  COMPOSITION  OF  CARCASS  COMPOSITES  OP 
MAINTENANCE  SHEEP 


Sheep  No. 

Dry 

substance 

Crude 
protein 

Ether 
extract 

Crude 
ash 

Unac- 
counted 
for 

Gross 
energy 
per  gram 

142.. 

perct. 
45.47 

perct. 
17.88 

perct. 
20.15 

perct. 
5.70 

perct. 
1.74 

small  cols. 
2  980 

143  

43.11 

18.94 

15.86 

5.78 

2.53 

2  630 

146  

40  80 

19  00 

15  09 

5  72 

99 

2  543 

148.. 

47.06 

17.94 

22.10 

5.15 

1.87 

3  032 

150  

41.37 

20.13 

14.37 

5.79 

1.08 

2  508 

151  

48  08 

17.44 

23  81 

5.39 

1.44 

3  343 

Average  .... 

44.32 

18.56 

18.56 

5.59 

1.61 

2  839 

TABLE  8. — PERCENTAGE  COMPOSITION  OF  OFFAL  SAMPLES  OF  MAINTENANCE  SHEEP 


Sheep 
No. 

Dry 

sub- 
stance 

Crude 
protein 

Ether 
extract 

Crude 
ash 

Unac- 
counted 
for 

Gross 
energy 
per  gram 

cr 

142.  .  . 

perct. 
37.04 

perct. 
14.19 

perct. 
17.57 

perct. 
3.61 

perct. 
1.67 

small 
cols. 
2  364 

143  

34.  881 

14.  291 

16.  121 

3.011 

1.46 

2  4101 

146  

31.95 

14.94 

13.02 

2.94 

1.05 

2  188 

148  

35.64 

13.75 

17.78 

2.49 

1.62 

2  679 

150  

34.  881 

14.  291 

16  .  121 

3.011 

1.46 

2  4101 

151  

34.  881 

14.  291 

16  .  12l 

3.011 

1.46 

2  4101 

Average..  .  . 

34.88 

14.29 

16.12 

3.01 

1.45 

2  410 

Samples  of  offal  from  Sheep  Nos.  143,  150,  and  151  were  accidentally  thrown  out 
before  they  were  analyzed.  The  average  percentage  composition  of  the  offal  sam- 
ples of  Sheep  Nos.  142,  146,  and  148  was  assumed  in  these  cases. 


from  the  pelts,  weighed  for  each  sheep,  and  a  sample  prepared  from 
the  composite  wool  for  the  group.  The  skin  was  leached  with  water  to 
remove  most  of  the  depilatory.  It  was  then  weighed,  cut  up  into  con- 
venient pieces,  and  put  thru  the  power  mill.  All  of  the  skins  were 
composited  into  one  sample  and  analyzed.  The  change  in  the  water 
content  of  the  skins  during  leaching  was  determined  by  the  difference 
between  the  weight  of  the  fresh  pelts  minus  the  wool,  and  the  weight 
of  the  leached  hides. 


1926] 


FEED  REQUIREMENTS  OF  SHEEP 


233 


All  samples  were  preserved  with  exactly  1  percent  of  powdered 
thymol  intimately  mixed  into  the  sample,  and  were  kept  in  the  refrig- 
erator at  a  low  temperature  until  analyzed.  The  analytical  figures 
were  corrected  for  this  small  amount  of  thymol.  The  samples  were 
analyzed  according  to  the  methods  of  the  Association  of  Official  Agri- 
cultural Chemists.  A  Parr  oxygen  bomb  calorimeter  was  used  to  de- 
termine directly  the  gross  energy  of  all  samples. 

The  results  of  these  chemical  analyses  of  the  various  samples  are 
contained  in  Tables  7,  8,  and  9,  and  the  computed  composition  of  the 
entire  carcass  is  given  in  Table  10.  The  results  in  Table  10  are  given 

TABLE  9. — PERCENTAGE  COMPOSITION  OF  COMPOSITE  SKIN  AND  WOOL  SAMPLES 
FROM  MAINTENANCE  SHEEP 


Sample 

Dry 

sub- 
stance 

Crude 
protein 

Ether 
extract 

Crude 
ash 

Unac- 
counted 
for 

Gross 
energy 
per  gram 

Skin  

perct. 
28.87 

perct. 
20.43 

perct. 
6.75 

perct. 
1.70 

perct. 
-    .01 

small 
cals. 
1  816 

Wool  

88.60 

63.31 

8.44 

8.94 

7.91 

4  312 

TABLE  10. — COMPOSITION  OF  MAINTENANCE  SHEEP 


•)     • 

Sheep 
No. 

Weight  of  sheep 

Dry 
sub- 
stance 

Crude 
protein 

Crude 
fat 

Crude 
ash 

Gross 
energy 

Total 

Empty 

kgs. 

kgs. 

kgs. 

kgs. 

kgs. 

kgs. 

therms 

142  

38.24 

31.72 

12.72 

5.51 

5.24 

1.44 

81.07 

143  

36.80 

28.69 

10.93 

5.17 

3.92 

1.24 

67.88 

146  

36.65 

31.49 

11.74 

5.92 

4.05 

1.41 

73.32 

148... 

33.88 

28.95 

12.21 

5.20 

.    5.29 

1.19 

79.95 

150  

34.90 

28.94 

10.97 

5.47 

3.82 

1.30 

67.86 

151  

34.90 

29.54 

12.39 

5.21 

5.47 

1.27 

83.55 

Average 

35.90 

29.87 

11.83 

5.41 

4.63 

1.31 

75.60 

in  terms  of  weights  of  the  different  constituents  and  total  therms  of 
gross  energy.  In  Table  11  these  weights  of  constituents  are  stated  as 
percentages  of  the  empty  weight  of  the  sheep,  the  gross  energy  being 
expressed  in  small  calories  per  gram  of  empty  weight.  These  carcasses 
in  all  cases  contained  a  smaller  percentage  of  fat  than  any  of  the  car- 
casses analyzed  by  Lawes  and  Gilbert.1 

Since  these  analyses  are  of  interest  mainly  in  the  computation  of 
the  gains  of  the  fat  sheep,  a  detailed  discussion  of  them  here  is  unnec- 
essary. 


42.    1925. 


and  Moulton.  The  Animal  as  a  Converter  of  Matter  and  Energy, 


234 


BULLETIN  No.  283 


[December, 


TABLE  11.- 


-PERCENTAGE  COMPOSITION  OP  MAINTENANCE  SHEEP  ON  THE 
BASIS  OF  THE  EMPTY  WEIGHT 


Sheep  No. 

Dry 

sub- 
stance 

Crude 
protein 

Crude 
fat 

Crude 
ash 

Gross 
energy 
per  gram 

142  

perct. 
40.1 

perct. 
17  A 

perct. 
16.5 

perct. 
4  5 

small 
cals. 
2  556 

143  

38.1 

18.0 

13.7 

4.3 

2  366 

146  

37.3 

18.8 

12.9 

4.5 

2  328 

148  

42  2 

18.0 

18  3 

4  1 

2  762 

150  

37.9 

18.9 

13.2 

4.5 

2  345 

151  

41.9 

17.6 

18.5 

4.3 

2  828 

Average  

39.58 

18.12 

15.52 

4.37 

2  531 

TABLE  12. — WEEKLY  WEIGHTS  OF  SHEEP  DURING  THE  FATTENING  PERIOD 
(All  weights  in  pounds) 


Sheep  No  

144 

145 

147 

159 

152 

153 

1923 
July  9  

84 

90 

91 

88 

85 

85 

July  16  

85 

87 

91 

85 

83 

82 

July  23  

91 

98 

98 

95 

91 

89 

July  30  

89 

95 

93 

95 

92 

88 

Aug.  6  

89 

100 

94 

95 

93 

88 

Aug.  13  

90 

100 

98 

97 

92 

89 

Aug.  20  

94 

105 

101 

102 

100 

93 

Aug.  27  

92 

104 

99 

99 

95 

92 

Sept.  3  

95 

111 

103 

106 

101 

95 

Sept.  10  

94 

106 

103 

105 

99 

96 

Sept.  17  

92 

112 

105 

106 

102 

96 

Sept.  24  

97 

112 

104 

107 

102 

97 

Oct.  1  

99 

112 

106 

111 

103 

99 

Oct.  8  

99 

117 

104 

111 

104 

100 

Oct.  15  

100 

117 

102 

110 

101 

100 

Oct.  22  

105 

120 

107 

Oct.  29  

109 

101 

100 

Nov.  5  

117 

106 

106 

Nov.  12  

105 

125 

106 

119 

110 

109 

Nov.  19  

101 

125 

104 

119 

105 

104 

Nov.  26  

104 

130 

109 

120 

105 

106 

Dec.  3  

104 

126 

110 

122 

106 

106 

Dec.  10  

100 

125 

109 

120 

108 

105 

Dec.  17  

97 

121 

109 

121 

106 

104 

Dec.  24  

101 

127 

114 

122 

108 

105 

Dec.  31  

98 

127 

115 

122 

109 

102 

Jan.  7  '... 

101 

130 

118 

127 

110 

104 

FEED  REQUIREMENTS  OF  SHEEP  235 

THE  FATTENING  EXPERIMENT 

The  fattening  experiment  was  started  on  July  9,  1923,  and  was 
continued  until  it  was  evident  that  a  majority  of  the  6  sheep  would 
not  put  on  any  more  weight  on  the  experimental  ration  of  alfalfa  hay 
alone.  In  fact,  when  the  sheep  were  slaughtered  on  January  7,  182 
days  after  their  rations  were  increased  from  the  maintenance  level,  3  of 
the  sheep  had  been  at  their  maximum  weights  for  the  last  8  or  10 
weeks,  as  the  weight  records  in  Table  12  indicate. 

During  the  fattening  of  these  sheep  the  attempt  was  made  to  get 
them  to  consume  as  much  of  the  hay  as  possible,  since  it  was  realized 
that  under  the  best  of  conditions  the  rate  of  gain  would  be  small  on  a 
ration  of  roughage  alone.  -They  were  started  on  3  pounds  of  alfalfa 
hay  daily  and  this  amount  was  raised  gradually  to  a  level  of  from  4  to 
6  pounds.  Toward  the  end  of  the  experiment  it  was  found  expedient 
to  lower  these  quantities  because  of  the  large  amounts  of  refused  feed. 
All  refused  feed  was  weighed  and  collected  for  analysis  in  periods  cor- 
responding with  those  for  which  feed  samples  were  obtained.  In  spite 
of  the  reduction  of  feed  toward  the  end  of  the  experiment,  increasing 
amounts  of  feed  were  refused.  It  was  found,  however,  from  the  chem- 
ical analyses  of  these  samples  of  refused  feed  that  while  at  first  the 
refused  feed  consisted  mainly  of  stems  containing  large  amounts  of 
crude  fiber,  towards  the  last,  as  the  amounts  of  refused  feed  increased, 
ytheir  composition  approached  that  of  the  alfalfa  hay  offered. 

The  total  feed  records  for  the  entire  fattening  experiment,  divided 
into  subperiods  corresponding  with  the  intervals  at  which  composite 
feed  and  ort  samples  were  analyzed,  are  given  in  Table  13.  In  this 
table  the  estimated  quantities  of  alfalfa  hay  consumed  do  not  have 
any  definite  significance,  particularly  in  tke  later  periods  of  the  ex- 
periment, since  the  weights  of  refused  feed  included  an  unknown  mois- 
ture contamination  from  the  sheep  themselves. 

In  Table  14  the  total  nutrients  consumed  by  the  fattening  sheep 
for  the  entire  period  of  182  days  are  given.  These  figures  were  obtained 
by  deducting  from  the  quantities  of  the  chemical  constituents  in  the 
alfalfa  hay  offered,  the  quantities  of  the  chemical  constituents  in  the 
hay  refused. 

In  view  of  the  considerable  amounts  of  alfalfa  hay  refused  in  this 
experiment,  there  was  some  danger  that  the  significance  of  the  results 
would  be  considerably  impaired  by  the  fact  that  the  composition  of  the 
material  actually  consumed  by  the  sheep  might  be  distinctly  different 
from  the  composition  of  the  alfalfa  hay  offered.  The  percentages  given 
in  Table  15  were  therefore  computed,  the  dry  substance  rather  than 
the  fresh  substance  being  used  as  the  basis  of  computation.  Table  15 
also  contains  the  average  dry-matter  composition  of  the  alfalfa  hay 
offered.  The  differences  in  dry-matter  composition  between  the  alfalfa 


236 


BULLETIN  No.  283 


[December, 


TABLE  13. — FEED  RECORDS  FOR  FATTENING  SHEEP 
(All  weights  in  pounds) 


Sheep  No  

144 

145 

147 

149 

152 

153 

July  9  to  Sept.  10,  63  days 
Alfalfa  offered  

185.5 

203.0 

185.5 

185.5 

185.5 

185  5 

Orts  

.7 

.7 

1.2 

1.6 

1.4 

3.4 

Consumed  

184.8 

202.3 

184.3 

183.9 

184.1 

182.1 

Sept.  10  to  Oct.  8,  28  days 
Alfalfa  offered  •  

126.0 

154.0 

126.0 

126.0 

126.0 

98.0 

Orts  

5.1 

4.5 

12.3 

4.3 

8.6 

7.1 

Consumed  

120.9 

149.5 

113.7 

121.7 

117.4 

90.9 

Oct.  8  to  Nov.  12,  35  days 
Alf  alf  a  offered  

175.0 

210.0 

175.0 

175.0 

175.0 

140  0 

Orts  

11.4 

11.6 

17.2 

11.9 

14.1 

8.4 

Consumed  

163.6 

198  4 

157.8 

163.1 

160  9 

131  6 

Nov.  12  to  Jan.  7,  56  days 
Alfalfa  offered  

224.0 

280.0 

224.0 

224.0 

224.0 

168  0 

Orts  

56.7 

24.6 

46.1 

31.2 

67.8 

31.9 

Consumed  

167.3 

225  A 

177.9 

192.8 

156.2 

136.1 

Total  period,  182  days 
Alfalfa  offered  

710.5 

847.0 

710.5 

710.5 

710  5 

591  5 

Alfalfa  refused  

73.9 

71.4 

76.8 

49.0 

91.9 

50.8 

Alfalfa  consumed  

636.6 

775.6 

633.7 

661  5 

618  6 

540  7 

Alfalfa  consumed,  kilograms.  .  . 

(289.4) 

(352.6) 

(288.0) 

(300.7) 

(281.2) 

(245.8) 

TABLE  14. — TOTAL  NUTRIENTS  CONSUMED  BY  FATTENING  SHEEP 


Sheep 
No. 

Dry 
sub- 
stance 

Crude 
protein 

N-free 

extract 

Crude 
fat 

Ash 

Crude 
fiber 

Gross 
energy 

kgs. 

kgs. 

kgs. 

kgs. 

kgs. 

kgs. 

therms 

144.. 

27  5  A 

49.2 

119.4 

6.2 

22.0 

78.6 

1  225 

145..   . 

334.  2T 

58.9 

144.2 

7.4 

26.4 

97.2 

1  483 

147..  . 

272.9 

47.8 

117.5 

6.1 

21.3 

80.4 

1  212 

149..   . 

283.2 

50.0 

122.0 

6.3 

22.3 

82.7 

1  259 

152..  . 

268.2 

47.8 

111.6 

6.1 

21.4 

81.4 

1  192 

153..   . 

231.5 

41.3 

99.6 

5.2 

18.2 

67.2 

1  033 

hay  consumed  and  the  alfalfa  hay  offered  seem  too  small  to  be  of  any 
serious  consequence  in  the  interpretation  of  the  feed  records. 

During  the  fattening  period,  digestion  and  metabolism  studies 
were  made  on  each  of  the  6  sheep.  However,  the  feed  consumption 
during  these  periods  was  so  variable  that  no  confidence  has  been  felt 
in  the  significance  of  the  coefficients  of  digestibility  obtained  or  in  the 
observed  utilization  of  the  gross  energy  of  the  feed.1  The  coefficients 
computed  were  generally  higher  than  those  obtained  during  the  main- 


*Bul.  Natl.  Research  Council  6,  pt.  2,  No.  33,  p.  20.    1923. 


1926] 


FEED  REQUIREMENTS  OF  SHEEP 


237 


tenance  experiment,  and  the  computed  metabolizable  energy  consti- 
tuted a  considerably  higher  percentage  of  the  gross  energy,  i.  e.,  52 
percent.  It  was  decided,  therefore,  to  discard  the  results  of  these  studies 
and,  in  all  future  computations,  to  rely  upon  the  analogous  results  ob- 
tained during  the  maintenance  experiment.  It  has  been  found  by 
other  investigators  that  with  rations  consisting  entirely  of  roughage, 
the  quantity  fed  apparently  has  no  effect  upon  the  digestibility.1 

A  summary  of  the  more  significant  slaughter  data  on  the  fat  sheep 
will  be  found  in  Table  16.  The  percentage  of  "fill"  on  these  sheep  was 
very  much  the  same  as  that  on  the  maintenance  sheep.  The  interval 

TABLE  15. — AVERAGE  PERCENTAGE  COMPOSITION  OP  ALFALFA  HAY  OFFERED  TO 
AND  CONSUMED  BY  THE  FATTENING  SHEEP  FOR  THE  ENTIRE  FATTENING  PERIOD 

(Results  expressed  on  dry  basis) 


Sheep  No. 

Crude 
protein 

N-free 
extract 

Crude 
fat 

Ash 

Crude 
fiber 

Gross 
energy 
per  gram 

Alfalfa  hay  offered 


All  '..... 

perct. 
17.5 

perct, 
42.2 

perct. 
2.1 

perct. 
7.8 

perct. 
30.4 

cals. 
4.45 

Alfalfa  hay  consumed 


144.  .  . 

17.9 

43.4 

2.3 

8.0 

28.5 

4.45 

145  

17.6 

43.1 

2.2 

7.9 

29.1 

4.44 

147  

17.5 

43.1 

2.2 

7.8 

29.5 

4.44 

149  

17.7 

43.1 

2.2 

7.9 

29.2 

4.45 

152  

17.8 

41.6 

2.3 

8.0 

30.4 

4.44 

153  

17.8 

43.0 

2.2 

7.9 

29.0 

4.46 

Average  

17.7 

42.9 

2.2 

7.9 

29.3 

4.45 

from  the  time  of  the  last  feeding  to  the  time  of  slaughter,  however, 
was  somewhat  shorter  with  these  sheep  than  with  the  maintenance 
sheep.  The  maintenance  sheep  were  fed  once  daily  at  approximately 
10  a.  m.  The  fat  sheep  were  fed  twice  daily  at  approximately  8  a.  m. 
and  4  p.  m.  The  fat  sheep  were  slaughtered  on  the  morning  of  January 
7  and  had  received  their  last  feed  at  4  p.  m.  the  preceding  day. 

The  average  dressing  percentage  of  the  fat  sheep  was  47.49,  a 
figure  very  close  to  the  average  dressing  percentage  of  the  maintenance 
sheep,  in  spite  of  the  fact  that  the  fat  sheep  were  in  higher  condition. 
However,  the  fat  sheep  possessed  a  heavier  coating  of  wool,  averaging 
3.47  kilograms,  as  compared  with  1.07  kilograms  for  the  maintenance 
sheep.  The  average  percentage  of  boneless  meat  in  the  cold  carcass 
was  82.5  as  compared  with  75.0  for  the  maintenance  sheep. 


'Armsby.  The  Nutrition  of  Farm  Animals,  613.   1917. 


238 


BULLETIN  No.  283 


[December, 


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1926'} 


FEED  REQUIREMENTS  OF  SHEEP 


239 


The  methods  of  sampling  in  the  analysis  of  these  carcasses  were 
the  same  as  those  used  for  the  maintenance  sheep,  with  the  exception 
that  the  hides  were  not  leached  before  making  up  the  sample.  The 
results  of  these  analyses  are  given  in  Tables  17,  18,  and  19.  Both  the 


TABLE  17. — PERCENTAGE  COMPOSITION  OF  THE  COMPOSITE  SAMPLES  OF  THE 
CARCASSES  OF  THE  FAT  SHEEP 


Sheep  No. 

Dry 

sub- 
stance 

Crude 
protein 

Ether 
extract 

Crude 
ash 

Unac- 
counted 
for 

Gross 
energy 
per  gram 

144... 

perct. 
48.88 

perct. 
16.81 

perct. 
26.35 

perct. 
4.67 

perct. 
1.05 

small 
cals. 
3  436 

145  

50.98 

15.69 

28.91 

4.77 

1.55 

3  588 

147  

50.68 

15.31 

28.58 

5.79 

1.00 

4  196 

149... 

54.52 

15.13 

33.84 

4.53 

1.02 

4  095 

152  

53.77 

15.25 

32.23 

4.24 

2.07 

3  944 

153  

49.54 

14.88 

29.12 

4.21 

1.33 

3  679 

Average  

51.39 

15.51 

29.84 

4.70 

1.34 

3  823 

TABLE  18. — PERCENTAGE  COMPOSITION  OF  SAMPLES  OF  OFFAL  FROM  FAT  SHEEP 


Sheep  No. 

Dry 

sub- 
stance 

Crude 
protein 

Ether 
extract 

Crude 
ash 

Unac- 
counted 
for 

Gross 
energy 
per  gram 

144.. 

perct. 
35  77 

perct. 
12  94 

perct. 
17  52 

perct. 
2.52 

perct. 
2  79 

small 
cals. 
2  448 

145  

42.40 

12.06 

25.63 

2.44 

2.27 

3  191 

147  

42.19 

12  19 

25.37 

2.13 

2.50 

3  252 

149.. 

42  80 

12  00 

26  36 

2.08 

2  36 

3  259 

152  

40.68 

12.62 

23.83 

2.07 

2.16 

3  131 

153  

42  81 

11  94 

26.34 

2.07 

2.46 

3  404 

Average  

41.11 

12.29 

24.18 

2.22 

2.42 

3  114 

TABLE  19. — PERCENTAGE  COMPOSITION  OF  COMPOSITE  SKIN  AND  WOOL 
SAMPLES  OF  FAT  SHEEP 


Sample 

Dry 

sub- 
stance 

Crude 
protein 

Ether 
extract 

Crude 
ash 

Unac- 
counted 
for 

Gross 
energy 
per  gram 

Skin  

perct. 
26.66 

perct. 
14.43 

perct. 
7.40 

perct. 
1.571 

perct. 
3.26 

small 
cals. 
1  849 

Wool  

85.73 

55.38 

12.12 

11.90 

6.30 

4  301 

Corrected  for  the  depilatory  used  by  assuming  that  the  ratio  of  organic  matter 
to  ash  was  the  same  for  this  skin  sample  as  for  the  skin  sample  from  the  maintenance 
sheep.  The  dry-matter  percentage  has  also  been  corrected  to  correspond  with  this 
assumption. 


240 


BULLETIN  No.  283 


[December, 


carcass  composite  and  the  offal  sample  of  the  fat  sheep  were  on  the 
average  distinctly  higher  in  dry  matter,  ether  extract,  and  gross  energy, 
and  distinctly  lower  in  crude  protein  and  ash,  than  the  corresponding 
samples  for  the  maintenance  sheep.  The  wool  of  the  fat  sheep  con- 
tained less  dry  matter  and  protein,  but  more  ether  extract  and  ash, 
than  the  wool  from  the  maintenance  sheep.  The  energy  value  of  the 
wool  was  about  the  same  for  both  groups  of  sheep. 

From  the  composition  and  weights  of  the  chemical  samples,  the 
composition  of  the  entire  carcass  was  computed,  the  results  being  given 
in  Table  20.  These  results  are  expressed  as  percentages  of  the  empty 
weights  of  the  sheep  in  Table  21.  A  comparison  of  this  table  with 
Table  11  is  of  interest.  The  maintenance  sheep  averaged  39.58  per- 

TABLE  20. — COMPOSITION  OF  FAT  SHEEP 


Sheep 
No. 

Weight  of  sheep 

Dry 

sub- 
stance 

Crude 
protein 

Crude 
fat 

Crude 
ash 

Gross 
energy 

Total 

Empty 

144  

kgs. 
46.58 
59.67 
54.32 

58.15 
51.17 

48.17 

kgs. 
39.20 
50.72 
45.22 

47.86 
42.67 
40.99 

kgs. 
17.59 
23.45 
20.68 

23.01 
20.25 
19.18 

kgs. 
7.28 
8.46 
7.51 

7.54 
7.04 
6.89 

kgs. 
7.78 
11.80 
10.17 

12.79 
10.58 
9.81 

kgs. 
1.72 
2.12 
2.13 

1.86 
1.65 
1.62 

therms 
116.15 
160.89 
157.06 

167.70 
143.23 
137.23 

145  

147  

149  

152  

153  

Average 

53.01 

44.44 

20.69 

7.45 

10.49 

1.85 

147.04 

TABLE  21. — PERCENTAGE  COMPOSITION  OP  FAT  SHEEP  ON  BASIS  OF  EMPTY  WEIGHT 


Sheep  No. 

Dry 

sub- 
stance 

Crude 
protein 

Crude 
fat 

Crude 
ash 

Gross 
energy 
per  gram 

144  

perct. 
44.9 

perct. 
18.6 

perct. 
19.8 

perct. 
4.4 

small 
cals. 
2  963 

145  

46.2 

16.7 

23.3 

4.2 

3  172 

147  

45.8 

16.6 

22.5 

4.7 

3  473 

149  

48.1 

15  7 

26  7 

3.9 

3  504 

152  

47.5 

16.5 

24.8 

3.9 

3  357 

153  

46.8 

16.8 

23.9 

4.0 

3  348 

Average  

46.55 

16.82 

23.51 

4.18 

3  303 

cent  dry  substance,  as  compared  with  46.55  percent  dry  substance  for 
the  fat  sheep.  The  average  protein  content  of  the  maintenance  sheep 
was  18.12  percent,  as  compared  with  16.82  percent  for  the  fat  sheep. 
The  maintenance  sheep  contained  an  average  of  15.52  percent  fat, 
while  the  fat  sheep  contained  an  average  of  23.51  percent  fat.  The 


1926} 


FEED  REQUIREMENTS  OF  SHEEP 


241 


ash  content  of  the  two  groups  of  sheep  was  very  nearly  the  same,  4.37 
percent  for  the  maintenance  sheep  and  4.18  percent  for  the  fat  sheep. 
From  the  average  weight  of  the  fat  sheep  from  the  date  of  shear- 
ing to  the  end  of  the  maintenance  experiment,  and  from  the  average 
composition  of  the  maintenance  sheep  at  the  time  of  slaughter,  the 
initial  composition  of  the  fat  sheep  was  computed.  Subtracting  the 
estimated  weights  of  constituents  in  the  sheep  at  the  beginning  of  the 
fattening  experiment  from  the  determined  weights  at  the  time  of 
slaughter,  gives  the  estimated  weights  added  to  the  carcasses  during 
the  fattening  period.  These  may  then  be  expressed  as  percentages  of 
the  gains  in  the  empty  weights  of  the  sheep.  (Table  22) . 

TABLE  22. — COMPUTATIONS  OF  THE  COMPOSITION  OF  THE  GAINS  OF  THE  FAT  SHEEP 
(Percentage  composition  of  gains  is  calculated  from  the  gains  in  empty  weight) 


Sheep 
No. 

Weights  and  gains 

Weights  and 
gains 

Dry 

sub- 
stance 

Crude 
protein 

Crude 
fat 

Crude 
ash 

Gross 
energy 

Total 

Empty 

144 
145 
147 
149 
152 
153 

Final  weight  .... 
Initial  weight  .  .  . 
Gain.  .        ... 

kgs. 
46.58 
38.41 

kgs. 
39.20 
32.00 

kgs. 
17.59 
12.67 

kgs. 

7.28 
5.80 

kgs. 
7.78 
4.97 

kgs. 
1.72 
1.40 

therms 
116.  151 
80.  991 

8.17 

7.20 

4.92 
(68.3) 

23.45 
13.43 

1.48 
(20.5) 

8.46 
6.15 

2.81 
(39.0) 

11.80 
5.26 

.32 

(4.4) 

2.12 

1.48 

35.  161 
2.222 

160.  891 

85.  851 

Percentage  com- 
position of  gain 

Final  weight  .... 
Initial  weight  .  .  . 
Gain  

59.57 
40.72 

50.72 
33.92 

18.85 

16.80 

10.02 
(60.0) 

20.68 
13.45 

2.31 

(13.7) 

7.51 
6.16 

6.54 
(38.9) 

10.17 

5.28 

.64 

(3.8) 

2.13 
1.49 

75.  041 
2.032 

157.  061 
86.  031 

Percentage  com- 
position of  gain 

Final  weight  .... 
Initial  weight  .  .  . 
Gain  

54.32 
40.80 

45.22 
33.99 

13.52 

11.23 

7.23 
(64.4) 

23.01 
13.38 

1.35 

(12.0) 

7.54 
6.13 

4.89 
(43.5) 

12.79 
5.25 

.64 

(5.7) 

1.86 

1.48 

71  .031 
2.882 

167.  701 
85.  571 

Percentage  com- 
position of  gain 

Final  weight.  .  .  . 
Initial  weight  .  .  . 
Gain  

58.15 
40.59 

47.86 
33.81 

17.56 

14.05 

9.63 

(68.5) 

20.25 
12.97 

1.41 
(10.0) 

7.04 
5.94 

7.54 

(53.7) 

10.58 
5.09 

.38 

(2.8) 

1.65 
1.43 

82.  131 
2.662 

143.  231 

S'2.941 

Percentage  com- 
position of  gain 

Final  weight  .... 
Initial  weight  .  .  . 
Gain  

51.17 
39.34 

42.67 
32.77 

11.83 

9.90 

7.28 
(73.5) 

19.18 
12.84 

1.10 

(H.l) 

6.89 

5.88 

5.49 

(55.5) 

9.81 
5.04 

.22 

(2.2) 

1.62 
1.42 

60.  291 

2.772 

H  .. 

137.  231 

82  .  131 

Percentage  com- 
position of  gain 

Final  weight  .... 
Initial  weight  .  .  . 
Gain  

48.17 
38.95 

40.99 
32.45 

9.22 

8.54 

6.34 

(74.2) 

1.01 

(11.8) 

4.77 
(55.9) 

.20 
(2.3) 

55.  101 
2.93» 

Percentage  com- 
position of  gain 

therms.    2Therms  per  pound. 


242 


BULLETIN  No.  283 


[December, 


TABLE  23. — COMPUTED  CHEMICAL  COMPOSITION  OF  GAINS  PUT  ON  BY 
FATTENING  SHEEP 


Sheep  No. 

Gain  in 
weight 

Dry 

sub- 
stance 

Crude 
pro- 
tein 

Crude 
fat 

Crude 
ash 

Gross 
energy 

Live 

Empty 

144.. 

kgs. 
8.17 
18.85 
13.52 

17.56 
11.83 
9.22 

kgs. 
7.20 
16.80 
11.23 

14.05 
9.90 

8.54 

kgs. 
4.92 
8.05 
7.23 

9.63 

7.28 
6.34 

kgs. 
1.48 
2.31 
1.35 

1.41 
1.10 
1.01 

kgs. 
2.81 
6.54 
4.89 

7.54 
5.49 

4.77 

kgs. 
.32 
.64 
.64 

.38 
.22 
.20 

therms 
35.2 
75.0 
71.0 

82.1 
60.3 
55.1 

145  

147  .. 

149  

152  

153  

Average  

13.19 

11.29 

7.24 

1.44 

5.34 

.40 

63.1 

TABLE  24.— PERCENTAGE  COMPOSITION  OF  GAINS  PUT  ON  BY  FATTENING  SHEEP 


Sheep  No. 

Dry 

sub- 
stance 

Crude 
protein 

Crude 
fat 

Crude 
ash 

Gross 
energy 
per  pound 

144.  . 

perct. 
68.3 

perct. 
20  5 

perct. 
39  0 

perct. 
4.4 

therms 
2.22 

145 

60  0 

13  7 

38  9 

3.8 

2.03 

147  

64.4 

12.0 

43.5 

5.7 

2.88 

149  

68  5 

10  0 

53  7 

2  8 

2.66 

152  

73.5 

11.1 

55.5 

2.2 

2.77 

153  

74.2 

11  8 

55.9 

2.3 

2.93 

Averdge  

68.1 

13.2 

47.7 

3.5 

2.58 

The  summary  of  the  composition  of  gains  by  actual  weight  and 
by  percentage  of  gain  in  empty  weight  is  given  in  Tables  23  and  24. 
From  the  latter  table,  it  will  be  seen  that  the  average  gain  in  empty 
weight  of  the  fat  sheep  contained  68.1  percent  dry  matter,  13.2  percent 
protein,  47.7  percent  crude  fat,  3.5  percent  ash,  and  2.58  therms  gross 
energy  per  pound  of  gain.  The  gain  in  dry  matter  contained  an  aver- 
age of  19.4  percent  protein,  70.0  percent  fat,  and  5.1  percent  ash. 

The  figures  just  quoted  refer  to  the  gain  in  empty  weight.  The 
gain  in  live  weight  would  contain  in  addition  a  certain  gain  in  "fill." 
Since  the  observed  percentage  of  "fill"  in  the  slaughtered  maintenance 
sheep  (16.7)  was  approximately  the  same  as  the  observed  percentage 
of  "fill"  in  the  slaughtered  fat  sheep  (16.1),  it  is  evident  that  the  aver- 
age gain  in  live  weight  must  have  contained  close  to  16  percent  of 
"fill."  This  conclusion  is  subject  to  some  slight  but  unknown  correc- 
tion, owing  to  the  fact  that  the  interval  between  the  last  feeding  and 
the  time  of  slaughter  was  longer  for  the  maintenance  sheep  than  for 
the  fat  sheep. 


FEED  REQUIREMENTS  OF  SHEEP 


243 


It  is  a  matter  of  considerable  importance  in  understanding  the 
nature  of  the  fattening  process  to  determine  not  only  the  composition 
of  gains  during  fattening,  but  also  the  manner  in  which  the  added  con- 
stituents are  distributed  thruout  the  different  parts  of  the  carcass.  In 
the  present  experiment,  of  the  total  increase  in  empty  weight  an  aver- 
age of  59.3  percent  was  in  the  dressed  carcass,  16.1  percent  in  the 
offal,  18.0  percent  in  the  wool,  and  6.6  percent  in  the  skin.  These  per- 
centages, of  course,  all  refer  to  the  fresh  weights  of  the  samples.  It  is 
of  particular  interest  to  note  that  of  the  59.3  percent  of  the  increase 
referable  to  the  dressed  carcass,  90.8  percent  was  in  the  boneless  meat. 
The  average  weight  of  bone  removed  from  the  dressed  carcass  of  the 
maintenance  sheep  was  4.18  kilograms,  and  the  average  weight  re- 
moved from  the  dressed  carcass  of  the  fat  sheep  was  4.31  kilograms. 
Evidently  the  skeletal  growth  of  the  fattened  sheep  practically  stopped 
during  the  182  days  on  the  increased  amounts  of  alfalfa  hay. 

The  average  distribution  of  the  gains  in  the  chemical  constituents 
during  the  fattening  among  the  different  carcass  samples  is  given  in 
Table  25.  It  is  evident  from  this  table,  that  the  carcass  composite  in- 
cluded the  major  portion  of  the  increase  in  most  of  the  constituents, 

TABLE  25. — PERCENTAGE  DISTRIBUTION  OF  THE  INCREASES  IN  THE  CHEMICAL  CON- 
STITUENTS OF  THE  FAT  SHEEP  AMONG  THE  DIFFERENT  CARCASS  SAMPLES 


Sample 

Dry 

matter 

Crude 
protein 

Crude 
fat 

Ash 

Gross 
energy 

Carcass,  composite  

perct. 
59  6 

perct. 
34  5 

perct. 
73.0 

perct. 
46.7 

perct. 
65.8 

Offal  

15  6 

5  3 

20  0 

0.0 

17.3 

Skin  

2  0 

0  0 

1  4 

1.7 

2.4 

Wool  

22.8 

60.2 

5.6 

51.6 

14.5 

Total  

100.0 

100.0 

100.0 

100.0 

100.0 

namely,  59.6  percent  of  the  dry  matter,  34.5  percent  of  the  crude  pro- 
tein, 73.0  percent  of  the  crude  fat,  46.7  percent  of  the  ash,  and  65.8 
percent  of  the  gross  energy.  Practically  all  of  this  material  was  added 
to  the  boneless  meat  of  the  carcass  rather  than  to  the  bones.  A  sur- 
prising feature  of  the  table  is  the  large  proportion  of  the  added  con- 
stituents contained  in  the  wool  grown  during  the  fattening  period, 
namely,  22.8  percent  of  the  dry  matter,  60.2  percent  of  the  protein, 
51.6  percent  of  the  ash,  14.5  percent  of  the  gross  energy,  and  5.6  poy- 
cent  of  the  crude  fat.  It  is  evident  that  a  preponderant  part  of  the 
material  added  to  the  bodies  of  sheep  during  fattening  is  recoverable 
in  the  marketable  products  of  the  carcass,  either  in  the  edible  part  of 
the  carcass  or  in  the  wool.  These  two  products  account  for  82.4  per- 
cent of  the  dry  matter,  94.7  percent  of  the  protein,  78.6  percent  of  the 
fat,  98.3  percent  of  the  ash,  and  80.3  percent  of  the  gross  energy  pro- 
duced during  fattening. 


244  BULLETIN  No.  283  [December, 

Much  the  same  situation  exists  with  reference  to  the  distribution 
of  added  nutrients  in  the  carcass  of  fattening  steers  and  swine.  From 
the  results  reported  from  the  Missouri  Station1  it  may  be  estimated 
that  the  increase  in  dry  matter  by  these  fattening  steers  contained  81 
percent  fat,  16  percent  protein,  and  3  percent  ash.  Furthermore,  from 
the  numerous  analyses  made  in  this  experiment,  it  may  be  computed 
that  94  percent  of  the  fat  gained  by  the  steers  in  the  feed  lot,  60  per- 
cent of  the  protein  so  gained,  and  about  90  percent  of  the  added  energy 
were  deposited  in  the  boneless  meat  and  edible  fat  in  the  carcass. 

Similarly,  from  experiments  performed  on  fattening  and  growing 
swine  at  the  Illinois  Station,2  it  may  be  computed  that  the  increase  in 
dry  matter  contained,  on  an  average,  71.1  percent  fat,  22.2  percent  pro- 
tein, and  6.6  percent  ash.  In  this  experiment  96  percent  of  the  added 
fat,  55  percent  of  the  added  protein,  and  90  percent  of  the  added  en- 
ergy were  deposited  in  the  boneless  meat  and  edible  fats  of  the  carcass. 

Evidently  such  computations  furnish  convincing  evidence  that  the 
gains  in  weight  which  farm  animals  put  on  during  a  period  of  intensive 
fattening  are  not  evenly  distributed  thruout  the  carcass,  but  are  mainly 
deposited  in  the  edible  portions,  or  in  portions  having  an  economic 
value  for  other  purposes.  In  making  comparisons  of  meat  animals 
with  dairy  cattle  and  farm  crops,  on  the  basis  of  economy  in  produc- 
tion of  human  food,  the  facts  just  reviewed  are  occasionally  disre- 
garded. Cooper  and  Spillman3  have  fallen  into  this  error.  In  com- 
puting the  amounts  of  protein  and  energy  that  can  be  produced  from 
an  acre  of  ground  by  feeding  the  crops  to  meat  animals,  they  first  com- 
puted the  gains  in  live  weight;  from  these  they  obtained  the  gains  in 
dressed  weight,  apparently  by  using  average  dressing  percentages  for 
the  different  classes  of  livestock ;  and  from  the  weights  of  dressed  meat, 
apparently  using  average  figures  for  the  protein  and  energy  content  of 
dressed  pork,  mutton,  and  beef,  they  obtained  the  total  production  of 
edible  protein  and  energy.  Such  calculations  are  based  upon  assump- 
tions directly  contrary  to  the  facts  above  illustrated,  and  result  in  a 
greatly  distorted  picture  of  the  inferiority  of  meat  animals  as  economic 
producers  of  human  food.  In  a  somewhat  similar  comparison  Armsby4 
also  has,  on  what  appear  to  be  the  same  grounds,  underestimated  the 
economic  value  of  steers  in  the  conversion  of  crops  into  edible  meat. 

The  results  of  the  present  experiment  afford  the  opportunity  of 
computing  the  content  of  protein  and  energy  in  the  daily  growth  of 


'Mo.  Agr.  Exp.  Sta.  Res.  Bui.  30.    1919. 

'111.  Agr.  Exp.  Sta.  Buls.  168,  169,  171,  173.     1914. 

"Cooper,  M.  O.,  and  Spillman,  W.  J.  Human  food  from  an  acre  of  staple 
farm  products.  U.  S.  Dept.  Agr.  Farmers'  Bui.  877.  1917.  See  also,  Third  Annual 
Report  of  the  Committee  on  Nutritional  Problems  of  the  American  Public  Health 
Association,  Amer.  Jour.  Pub.  Health  11,  166.  1921. 

4The  modern  science  of  food  values.    Yale  Review  (n.  s.)  9,  330.    1920. 


FEED  REQUIREMENTS  OF  SHEEP 


245 


wool  on  sheep.  During  the  182  days  of  the  fattening  period  of  this 
experiment  the  protein  content  of  the  added  wool  amounted  approxi- 
mately to  1,240  grams  per  head,  or  6.75  grams  (.0149  pound)  per  head 
daily.  Since  the  sheep  averaged  close  to  100  pounds  in  weight,  the 
protein  requirement  for  wool  production  amounted  approximately  to 
.15  pound  daily  per  1,000  pounds  live  weight.  This  figure  is  in  close 
agreement  with  the  similar  figure  computed  by  Armsby1  from  the  re- 
sults of  several  investigators;  namely,  .135  pound  per  1,000  pounds 
live  weight  per  day.  The  average  gross  energy  content  of  the  wool 
growth  made  during  the  fattening  period  was  10.3  therms  per  head,  or 
approximately  56.6  calories  per  head  per  day,  which  is  equivalent  to  a 
requirement  of  566  calories  per  1,000  pounds  live  weight  per  day. 

TABLE  26. — AVAILABILITY  OP  THE  METABOLIZABLE  ENERGY  op  ALFALFA  HAY  FOK 

FATTENING  SHEEP 


Sheep  No  

144 

145 

147 

149 

152 

153 

Days  on  experiment  

182 

182 

182 

182 

182 

182 

Final  weight  ...      .           .    . 

Ibs. 
102  7 

Ibs. 
131  6 

Ibs. 
119  8 

Ibs. 

128  2 

Ibs. 
112  8 

Ibs. 
106  2 

Initial  weigkt  

84.7 

89.8 

90.0 

89.5 

86.7 

85.9 

Gain  .    . 

18  0 

41  8 

29  8 

38  7 

26  1 

20  3 

Average  weight  

96.4 

113  0 

103.7 

109  0 

100  8 

99  9 

Metabolizable  energy  used  daily 
for  maintenance 
Per  100  pounds  weight  .  .  . 

therms 
1  82 

therms 
1  67 

therms 
1  75 

therms 
1  72 

therms 
1  58 

therms 
1  62 

Per  head  

1  77 

1  81 

1  79 

1  83 

1  59 

1  62 

Total  metabolizable  energy 
Consumed  

543 

621 

528 

569 

471 

411 

Used  for  maintenance  

323 

330 

326 

333 

290 

294 

Available  for  production  

Percentage  metabolizable  energy 
intake  available  for  production 

Gross  energy  of  gains  

220 

(40.5) 
35  16 

291 

(46.9) 
75.04 

202 

(38.3) 
71.03 

236 

(41.5) 
82.13 

181 

(38.4) 
60  29 

117 

(28.5) 
55  10 

Percentage   availability  of   the 
metabolizable   energy   of   al- 
falfa hay  for  fattening  sheep  .  . 

(16.0) 

(25.7) 

(35.1) 

(34.8) 

(33.3) 

(47.1) 

Calculations  involving  the  feed  records  of  the  6  fattened  sheep  in 
both  the  maintenance  and  the  fattening  periods,  and  the  computed 
energy  content  of  the  gains  during  fattening,  permit  an  estimation  of 
the  net  availability  of  the  metabolizable  energy  of  alfalfa  hay  for  fat- 
tening sheep.  Such  computations  are  given  in  Table  26. 

The  average  weights  and  gains  given  in  the  upper  part  of 
Table  26  need  no  explanation.  The  total  metabolizable  energy  con- 

*The  Nutrition  of  Farm  Animals,  327.    1917. 


246  BULLETIN  No.  283  [December, 

sumed  by  each  sheep  was  computed  from  the  total  intake  of  gross  en- 
ergy per  sheep,  given  in  Table  14,  and  the  percentage  of  the  gross  en- 
ergy of  alfalfa  hay  that  was  found  to  be  metabolizable  in  the  main- 
tenance trial  (Table  4).  The  percentage  used  for  each  sheep  in  the 
computation  of  the  metabolizable  energy  intake  was  the  percentage 
computed  for  that  particular  sheep  in  this  metabolism  trial.  The  justi- 
fication for  applying  this  result,  obtained  on  a  maintenance  ration,  to 
the  results  of  the  fattening  period  is  found  in  the  close  agreement  in 
average  composition  of  the  alfalfa  hay  fed  in  the  two  periods  (Table 
1),  and  the  experience  of  other  investigators  that  with  rations  consist- 
ing entirely  of  roughage,  the  digestibility  is  independent  of  the  quan- 
tity fed.  The  unsatisfactory  results  in  the  second  metabolism  period 
on  the  fattening  sheep,  while  they  were  consuming  increased  amounts 
of  alfalfa  hay,  precludes  their  use  in  this  connection.  The  metaboliz"- 
able  energy  required  for  maintenance  per  head  daily  was  computed 
from  the  individual  results  of  Table  5  applied  to  the  average  weight  of 
the  individual  sheep  in  the  fattening  period,  and  the  surface  ratio  being 
used  in  the  computation.  The  total  metabolizable  energy  used  for 
maintenance  was  obtained  simply  by  multiplying  the  daily  require- 
ment by  the  number  of  days  in  the  fattening  period.  The  remaining 
steps  in  the  final  computation  of  the  percentage  availability  of  the 
metabolizable  energy  of  alfalfa  hay  are  obvious.  The  percentages  ob- 
tained give  an  average  of  32.0  and  a  range  from  16.0  to  47.1.  Three 
of  the  6  sheep,  namely,  Nos.  147,  149,  and  152,'gave  percentages  agree- 
ing very  closely  among  themselves;  namely,  35.1,  34.8,  and  33.3.  The 
result  for  Sheep  145  is  not  far  removed  from  these  figures,  being  25.7 
percent.  The  extremely  low  result  of  16.0  and  the  extremely  high  re- 
sult of  47.1  were  obtained  with  the  two  sheep  gaining  the  least.  These 
percentages  are,  therefore,  presumably  less  accurate  than  the  other 
four,  since  the  greater  the  percentage  increase  in  weight  during  fatten- 
ing, the  smaller  will  be  the  effect  of  the  error  (common  to  all  slaugh- 
ter experiments)  involved  in  the  assumption  that  the  fattened  sheep 
possessed  the  same  composition  at  the  beginning  of  the  fattening  per- 
iod as  check  animals  killed  at  that  time.  The  average  of  the  four 
best-agreeing  percentages  was,  however,  closely  similar  to  the  average 
of  the  group  of  six,  namely,  32.2  percent  as  compared  with  32.0. 

The  alfalfa  hay  consumed  by  the  fattening  sheep  contained  4.45 
therms  of  gross  energy  per  kilogram  of  dry  matter  (Table  15).  From 
the  average  percentage  of  the  gross  energy  that  was  found  to  be  meta- 
bolizable during  the  maintenance  period,  namely  42.9  (Table  4) ,  it  may 
be  computed  that  the  alfalfa  hay  consumed  contained  1.91  therms  of 
metabolizable  energy  per  kilogram  of  dry  matter.  If  32  percent  of  the 
metabolizable  energy  of  alfalfa  hay  is  net  available  for  fattening  sheep 
(Table  26),  the  net  energy  value  becomes  611  calories  per  kilogram 
of  dry  matter. 


1926~\ 


FEED  REQUIREMENTS  OF  SHEEP 


247 


It  is  interesting  to  compare  the  results  of  this  experiment  with  the 
results  that  Armsby  and  his  associates  have  obtained  relative  to  the 
utilization  of  the  energy  of  alfalfa  hay  by  steers  on  sub-maintenance 
or  only  slightly  super-maintenance  rations.  In  Table  27  is  shown  a 
compilation  of  individual  determinations  by  these  investigators.  The 
computation  of  the  net  energy  in  these  experiments  has  been  carried 
out  according  to  the  revised  and  improved  method  of  Kriss.1  However, 


TABLE  27. — A  SUMMARY  OF  THE  DETERMINATION  OF  THE  UTILIZATION  OF  THE 

ENERGY  OF  ALFALFA  HAY  BY  STEERS 

(As  reported  by  Armsby  and  associates) 


Literature 
reference 

Experi- 
ment 
No. 

Steer 
No. 

Energy  per  kilogram  of  dry  matter 

Gross 

Metabolizable 

Net  available 

caZs. 

caZs. 

perct. 
of  gross 

cals. 

perct. 
of  meta- 
bolizable 

J.  Agr.  Res.  3, 
435.     1915 

208 
208 

C 
D 

4  405 
4  407 

1  820 
1  729 

41.3 
39.2 

684 
392 

37.6 

22.7 

208 

E 

4  408 

1  837 

41.7 

635 

34.6 

209 

F 

4  338 

1  810 

41.8 

671 

37.1 

212 

H 

4  368 

2  056 

47.1 

1  017 

49.5 

212 

H 

4  374 

2  012 

46.0 

895 

44.5 

J.  Agr.  Res.  IS, 
269.     1918 
Average  

J 

4  334 
4  376 

1  945 

1  887 

44.9 
43.1 

927 

746 

47.7 
39.1 

in  the  computations  given  in  Table  27  no  attempt  was  made  to  recal- 
culate the  heat  production  of  the  steers  to  a  standard  day  of  12  hours 
standing  and  12  hours  lying  down,  by  the  revised  method  of  Fries  and 
Kriss.2  The  authors  feel  some  hesitation  in  accepting  this  method  of 
calculating  heat  production  to  a  standard  day,  since  it  is  based  upon 
the  result  of  a  single  experiment,  which,  however  ideal,  can  hardly  be 
considered  an  adequate  basis  for  a  general  method  of  correcting  direct 
experimental  determinations.  In  all  probability  different  animals 
would  show  different  increments  in  heat  production  due  to  standing, 
even  when  equalized  for  differences  in  size,  because  of  differences  in 
the  degree  of  activity  in  the  standing  position.  Furthermore,  the  as- 
sumption involved  in  the  method,  that  the  extra  heat  production  due 
to  standing  (a  purely  muscular  function)  is  proportional  to  the  body 
surface  of  the  animal,  rather  than  to  its  weight,  seems  to  us  to  be  an 
unfortunate  confusion  of  ideas.  The  surface  law  relates  specifically 
to  the  basal  metabolism  of  animals.  It  cannot,  therefore,  be  legiti- 
mately applied  to  a  factor  in  the  heat  production  of  animals  that  re- 

1Armsby  and  Moulton.  The  Animal  as-  a  Converter  of  Matter  and  Energy, 
139-143.    1925. 

2Fries,  J.  A.,  and  Kriss,  Max.    Amer.  Jour.  Physiol.  71,  60.    1924. 


248  BULLETIN  No.  283  [December, 

lates  to  the  activity  of  the  voluntary  muscles,  even  tho  such  a  factor  is 
justifiably  included  in  what  has  been  called  the  "economic  mainten- 
ance" of  animals.  For  this  reason,  the  greater  the  difference  between 
the  energy  requirements  for  so  called  "economic  maintenance"  and  the 
minimum  energy  requirement  of  the  resting  animal,  the  less  applicable 
does  the  surface  law  become  in  the  computation  of  maintenance  ra- 
tions. Altho  the  method  that  Armsby  has  used  in  correcting  heat  pro- 
duction to  a  standard  day  is  of  questionable  accuracy,  as  Fries  and 
Kriss  point  out,  the  authors  are  not  convinced  that  the  new  method 
proposed  is  a  distinct  improvement. 

Referring  again  to  Table  27  it  will  be  noted  that  the  average  per- 
centage of  the  gross  energy  of  alfalfa  hay  represented  in  the  metaboli- 
zable  fraction,  namely,  43.1,  is  in  very  close  agreement  to  the  similar 
percentage  found  in  this  experiment  on  sheep,  namely,  42.9.  The  per- 
centage availability  of  the  metabolizable  energy  in  Armsby 's  experi- 
ments varied  widely  with  different  animals.  The  values  obtained  with 
Steers  C,  D,  E,  and  F,  averaging  33.0  percent,  are  closely  similar  to 
the  values  obtained  for  Sheep  145,  147,  149,  and  152.  The  three  values 
obtained  with  Steers  H  and  J  are  considerably  higher  than  the  other 
values  and  raise  the  average  percentage  to  39.1.  However,  because  of 
the  variability  among  individual  experiments,  it  cannot  be  concluded 
that  steers  are  any  more  efficient  in  the  utilization  of  the  metabolizable 
energy  of  alfalfa  hay  than  are  sheep. 

The  net  energy  content  of  alfalfa  hay  per  kilogram  of  dry  matter 
averaged  746  calories  for  steers,  as  compared  with  an  average  of  611 
calofies  for  sheep.  The  authors  hesitate,  however,  to  attach  any  sig- 
nificance to  this  average  difference.  Armsby  and  Moulton1  give  a  value 
of  915  calories  of  net  energy  per  kilogram  of  dry  matter  to  alfalfa  hay, 
based  upon  the  experiments  of  Armsby  and  Fries.  This  value  is  con- 
siderably higher  than  the  average  calculated  from  all  of  Armsby 's 
experiments  with  alfalfa  hay,  and  is  apparently  based  upon  the  re- 
sults of  Steers  H  and  J.  Until  an  adequate  explanation  for  discarding 
the  earlier  experiments  of  Armsby  and  Fries  has  been  given,  it  would 
seem  preferable  to  accept  the  average  computed  in  Table  27,  rather 
than  the  much  higher  value  given  by  Armsby  and  Moulton. 

Assuming  that  the  availability  of  the  metabolizable  energy  of 
alfalfa  hay  is  the  same  for  maintenance  as  for  fattening,  it  is  possible 
to  compute  the  net  energy  requirement  of  the  sheep  for  maintenance. 
An  average  of  1,733  calories  of  metabolizable  energy  per  100  pounds 
live  weight  was  required  for  this  purpose.  If  32  percent  of  this  energy 
is  net  available,  the  net  energy  required  for  maintenance  would  be  554 
calories  per  100  pounds  live  weight.  This  figure  is  considerably  lower 
than  the  figure  of  791  calories  computed  by  Armsby2  on  the  assump- 


'Loc.  cit.,  p.  145. 

2The  Nutrition  of  Farm  Animals,  294. 


1926"]  FEED  REQUIREMENTS  OF  SHEEP  249 

tion  that  52.8  percent  of  the  metabolizable  energy  of  roughages  and  55 
percent  of  the  metabolizable  energy  of  concentrates  was  available  for 
maintenance.  The  high  percentage  availability  assumed  for  roughage 
can  hardly  be  considered  a  good  average  figure  of  Armsby's  own  com- 
putations.1 However,  since  the  assumption  that  the  utilization  of  feed 
energy  is  the  same  for  sub-maintenance  as  for  super-maintenance  ra- 
tions is  still  debatable,  any  value  for  the  net  energy  requirement  of 
maintenance  based  upon  it  is  only  tentative. 

SUMMARY 

The  average  digestibility  of  alfalfa  hay  fed  as  a  maintenance  ra- 
tion to  the  12  sheep  in  this  investigation  is  represented  by  the  following 
coefficients:  dry  substance,  55.6;  crude  protein,  67.3;  nitrogen-free  ex- 
tract, 71.0;  ether  extract,  19.0;  and  crude  fiber,  26.3.  The  metaboliz- 
able energy  of  the  alfalfa  hay  was  found  to  equal,  on  an  average, 
42.9  percent  of  the  gross  energy.  Per  kilogram  of  dry  matter,  the  me- 
tabolizable energy  amounted  to  1.91  therms,  and  per  pound  of  digest- 
ible organic  matter,  1.69  therms. 

In  a  maintenance  period  lasting  126  to  133  days,  the  average 
amount  of  alfalfa  hay  required  by  the  12  sheep  per  100  pounds  live 
weight  was  2.295  pounds  daily,  computed  by  the  weight  ratio,  and 
2.185  pounds  daily,  computed  by  the  surface  ratio  (i.  e.,  the  ratio  of 
the  two-thirds  power  of  the  weights).  The  quantity  of  metabolizable 
energy  of  the  alfalfa  hay  required  for  maintenance  per  100  pounds  live 
weight  was  1,820  calories,  computed  by  the  weight  ratio,  and  1,733 
calories,  computed  by  the  surface  ratio. 

At  the  end  of  the  maintenance  experiment  6  of  the  sheep  were 
killed  and  analyzed.  The  remaining  6  were  put  upon  increased 
amounts  of  alfalfa  hay  for  a  fattening  period  of  182  days,  during 
which  time  the  gains  in  weight  totaled  from  18  to  42  pounds.  These 
sheep  were  then  slaughtered  and  analyzed.  The  increase  in  condition 
during  the  fattening  period  may  be  fairly  measured  by  the  average 
percentage  of  fat  in  the  maintenance  sheep  as  compared  with  the  fat 
sheep.  These  percentages,  on  the  dry  basis,  were  39  for  the  mainten- 
ance sheep  and  51  for  the  fat  sheep. 

An  average  of  16  percent  of  the  gain  in  the  live  weight  of  the 
sheep  during  the  fattening  period  was  accounted  for  by  a  gain  in  "fill." 
The  gain  in  empty  weight  contained,  on  an  average,  2.58  therms  of 
gross  energy  per  pound,  and  analyzed  68.1  percent  dry  substance,  13.2 
percent  protein,  47.7  percent  fat,  and  3.5  percent  ash.  The  gain  in  dry 
matter  contained  an  average  of  19.4  percent  protein,  70.0  percent  fat, 
and  5.9  percent  ash. 

Of  the  total  increase  in  chemical  constituents,  the  dressed  carcass 
contained  59.6  percent  of  the  dry  matter,  34.5  percent  of  the  crude  pro- 

'Ibid.,  661. 


250  BULLETIN  No.  283  [December, 

tein,  73.0  percent  of  the  crude  fat,  46.7  percent  of  the  ash,  and  65.8 
percent  of  the  gross  energy.  Practically  all  this  material  was  added 
to  the  boneless  meat  of  the  carcass.  A  large  proportion  of  the  chem- 
ical constituents  deposited  in  the  sheep  carcasses  during  the  fattening 
period  was  contained  in  the  growth  of  wool;  namely,  22.8  percent  of 
the  gain  in  dry  matter,  60.3  percent  of  the  gain  in  protein,  51.6  percent 
of  the  gain  in  ash,  14.5  percent  of  the  gain  in  gross  energy,  and  5.6 
percent  of  the  gain  in  crude  fat.  It  is  evident  that  a  preponderant  part 
of  the  material  added  to  the  bodies  of  sheep  during  fattening  is  recov- 
erable in  the  marketable  products  of  the  carcass,  i.  e.,  either  in  the 
edible  meat  of  the  dressed  carcass  or  in  the  wool.  In  this  particular 
experiment  these  two  products  accounted  for  82.4  percent  of  the  gain 
in  dry  matter,  94.7  percent  of  the  gain  in  protein,  78.6  percent  of  the 
gain  in  fat,  98.3  percent  of  the  gain  in  ash,  and  80.3  percent  of  the  gain 
in  gross  energy  produced  during  fattening. 

During  the  fattening  period  the  daily  growth  of  wool  contained 
.15  pound  of  protein  and  566  calories  per  1,000  pounds  live  weight  of 
sheep. 

It  has  been  computed  that  an  average  of  32  percent  of  the  meta- 
bolizable  energy  consumed  above  the  maintenance  requirement  by 
these  6  fattening  sheep  was  recovered  in  the  gross  energy  of  the  gains 
produced.  Four  of  the  individual  results  agreed  among  themselves 
fairly  well.  The  two  results  diverging  most  from  the  average  were  ob- 
tained with  those  sheep  gaining  the  least  in  weight,  and  therefore  are 
presumably  the  least  accurate  determinations.  However,  the  omission 
of  these  two  discordant  results  does  not  appreciably  change  the  aver- 
age percentage  availability  of  the  metabolizable  energy  of  alfalfa  hay 
in  fattening. 

In  the  alfalfa  hay  used  in  this  experiment  there  were  4.45  therms 
gross  energy,  1.91  therms  metabolizable  energy,  and  .611  therm  of  net 
energy  per  kilogram  of  dry  matter. 

In  seven  experiments  on  the  utilization  of  the  energy  of  alfalfa 
hay  by  steers  reported  by  Armsby  and  associates,  the  metabolizable 
energy  averaged  43.1  percent  of  the  gross  energy,  and  the  net  available 
energy  averaged  39.1  percent  of  the  metabolizable.  The  first  percent- 
age agrees  very  well  with  the  average  in  this  experiment,  while  the  sec- 
ond percentage  is  somewhat  higher.  However,  the  variation  among  in- 
dividual results  in  the  present  experiment,  as  well  as  in  the  experi- 
ments of  Armsby,  was  so  great  that  it  cannot  be  concluded  that  sheep 
are  inferior  to  steers  in  the  utilization  of  the  metabolizable  energy  in 
fattening.  Four  of  the  individual  results  obtained  by  Armsby  agree 
very  well  with  the  four  most  concordant  results  obtained  in  the  present 
experiment  with  sheep. 


1926'] 


FEED  REQUIREMENTS  OF  SHEEP 


251 


APPENDIX  TABLE  1. — DIGESTIBILITY  OF  ALFALFA  HAT  IN  THE 
MAINTENANCE  EXPERIMENT 


Dry 

substance 

Crude 
protein 

N-free 
extract 

Ether 
extract 

Crude 
ash 

Crude 
fiber 

Sheep  142 
Nutrients  consumed,  alfalfa  hay  
Nutrients  excreted,  feces  

grams 
5  834.9 
2  591  3 

grams 
943.4 
308.  1 

grams 
2  845.5 
784.6 

grams 
133.1 
121.7 

grams 
481.6 
231.6 

grams 
1  431.3 
1  145.3 

Nutrients  digested  

3  243  6 

635.3 

2  060.9 

11.4 

250.0 

286.0 

Coefficient  of  digestibility  

(55  6) 

(67.4) 

(72.4) 

(8.6) 

(51.9) 

(20.0) 

Sheep  143 
Nutrients  consumed,  alfalfa  hay.  .  .  . 
Nutrients  excreted,  feces  

5  834.9 
2  410  2 

943.4 
300  3 

2.845.5 
709.3 

133.1 

120  8 

481.6 
227.9 

1  431.3 
1  049.3 

Nutrients  digested  

3  424  7 

643  1 

2  136.2 

12  3 

253.7 

382.0 

Coefficient  of  digestibility  

(58  7) 

(68  2) 

(75.1) 

(9.2) 

(52.7) 

(26.7) 

Sheep  144 
Nutrients  consumed,  alfalfa  hay.  .  .  . 
Nutrients  excreted,  feces  

5  834.9 
2  491  7 

943.4 
307.  1 

2  845.5 
827.5 

133.1 
123.5 

481.6 
235.9 

1  431.3 

997.8 

Nutrients  digested  

3  343  2 

636.3 

2  018.0 

9.6 

245.7 

443.5 

Coefficient  of  digestibility  

(57  3) 

(67.5) 

(70.9) 

(7.2) 

(51.0) 

(30.3) 

Sheep  145 
Nutrients  consumed,  alfalfa  hay.  .  .  . 
Nutrients  excreted,  feces  

5  892.9 
2  612  5 

975.3 
303  4 

2  614.9 

823.4 

122  3 
107.6 

552.3 
251.4 

1  628.2 
1  126.8 

Nutrients  digested  

3  280  4 

671  9 

1  791.5 

14.7 

300.9 

501.4 

Coefficient  of  digestibility  

(55  7) 

(68  9) 

(68.5) 

(12.0) 

(54.5) 

(30.8) 

Sheep  146 
Nutrients  consumed,  alfalfa  hay.  .  .  . 
Nutrients  excreted,  feces  

5  892.9 
2  462  7 

975.3 
309.4 

2  614.9 

738.8 

122.3 

88.7 

552.3 
253.4 

1  628.2 
1  072.4 

Nutrients  digested  

3  430  2 

665  9 

1  876.1 

33.6 

298.9 

555.8 

Coefficient  of  digestibility  

(58  2) 

(68.3) 

(71.7) 

(27.4) 

(54.1) 

(34.1) 

Sheep  147 
Nutrients  consumed,  alfalfa  hay.  .  .  . 
Nutrients  excreted,  feces  

5  892.9 
2  388  9 

975.3 
308  3 

2  614.9 
713.1 

122.3 
90.0 

552.3 
244.1 

1  628.2 
1  033.5 

Nutrients  digested  

3  504  0 

667  0 

1  901.8 

32.3 

308.2 

594.7 

Coefficient  of  digestibility  

(59  5) 

(68  4) 

(72.7) 

(26.4) 

(55.8) 

(36.5) 

Sheep  148 
Nutrients  consumed,  alfalfa  hay.  .  .  . 
Nutrients  excreted,  feces  

5  840.0 
2  734   1 

995.6 
353  5 

2  621.9 
769  0 

110.2 
64.9 

519.8 
260.8 

1  592.5 
1  285.9 

Nutrients  digested  

3  105  9 

642   1 

1  852.9 

45.3 

259.0 

306.6 

Coefficient  of  digestibility  

(53  2) 

(64  5) 

(70.7) 

(41,1) 

(49.8) 

(19.3) 

Sheep  149 
Nutrients  consumed,  alfalfa  hay  .  .  .  . 
Nutrients  excreted,  feces  

5  840.0 
2  501  9 

995.6 
318  4 

2  621.9 
737.0 

110.2 
72.4 

519.8 
238.0 

1  592.5 
1  135.3 

Nutrients  digested  

3  338   1 

677  2 

1  884.9 

37.8 

281.8 

457.2 

Coefficient  of  digestibility  

(57  2) 

(68  0) 

(71.9) 

(34.3) 

(54  .  2  ) 

(28.7) 

Sheep  150 
Nutrients  consumed,  alfalfa  hay.  .  .  . 
Nutrients  excreted,  feces  

5  840.0 
2  641   1 

995.6 
345  8 

2  621.9 
809.1 

110.2 
60.  1 

519.8 
242.7 

1  592.5 
1   183.0 

Nutrients  digested  

3  198  9 

649.8 

1  812.8 

50.  1 

277.1 

409.5 

Coefficient  of  digestibility  

(54.8) 

(65.3) 

(69.1) 

(45.5) 

(53.3) 

(25.7) 

Sheep  151 
Nutrients  consumed,  alfalfa  hay.  .  .  . 
Nutrients  excreted,  feces  

5  781.4 
2  784  4 

919.8 
295.3 

2  721.9 

844.9 

126.8 
110.3 

402.0 
249.2 

1  611.0 
1  284.8 

Nutrients  digested  

2  997  0 

624  5 

1  877.0 

16.5 

152.8 

326.2 

Coefficient  of  digestibility  

(51  8) 

(67  9) 

(69.0) 

(13.0) 

(38.0) 

(20.2) 

Sheep  152 
Nutrients  consumed,  alfalfa  hay.  .  .  . 
Nutrients  excreted,  feces  

5  781.4 
2  702  2 

919.8 
303  8 

2  721.9 
791.7 

126.8 
123.0 

402.0 
235.7 

1  611.0 
1  248.1 

Nutrients  digested  

3  079  2 

616.0 

1  930.2 

3.8 

166.3 

362.9 

Coefficient  of  digestibility  

(53  3) 

(67.0) 

(70.9) 

(3.0) 

(41.4) 

(22.5) 

Sheep  153 
Nutrients  consumed,  alfalfa  hay.  .  .  . 
Nutrients  excreted,  feces  

5  781.4 
2  789  0 

919.8 
309.1 

2  721.9 

828.8 

126.8 
130.6 

402.0 
235.9 

1  611.0 
1  284.7 

Nutrients  digested  

2  992.4 

610.7 

1  893.1 

-3.8 

166.1 

326.3 

Coefficient  of  digestibility  

(51.8) 

(66.4) 

(69.6) 

(0.0) 

(41.3) 

(20.3) 

252 


BULLETIN  No.  283 


[December, 


APPENDIX  TABLE  2. — CHEMICAL  COMPOSITION  OF  FECES  IN  METABOLISM 
PERIODS  OF  MAINTENANCE  EXPERIMENT 


Sheep 
No. 

Dry 

substance 

Crude 
protein 

N-free 
extract 

Ether 
extract 

Crude 
ash 

Crude 
fiber 

Gross 
energy 
per  gram 

142... 

perct. 
66.02 

perct. 
7.85 

perct. 
19.99 

perct. 
3.10 

perct. 
5.90 

perct. 
29.18 

small  cals. 
3  120 

143  

61  88 

7  71 

18  21 

3  10 

5  85 

26  94 

2  936 

144  

56  31 

6  94 

17.70 

2  79 

5  33 

22  55 

2  667 

145... 

59.24 

6.88 

18.67 

2.44 

5.70 

25  55 

2  720 

146  

51.90 

6.52 

15.57 

1.87 

5.34 

22.60 

2  411 

147  

50.99 

6.58 

15.22 

1.92 

5.21 

22.06 

2  373 

148  

47.18 

6.10 

13.27 

1.12 

4.50 

22.19 

2  158 

149  

56  35 

7.17 

16.60 

1.63 

5.36 

25.57 

2  607 

150  

47.89 

6.27 

14.67 

1.09 

4.40 

21.45 

2  131 

151... 
152  

49.50 
55  60 

5.25 
6.25 

15.02 
16  29 

1.96 
2.53 

4.43 

4.85 

22.84 
25  68 

2  222 
2  657 

153       .   . 

56  40 

6  25 

16  76 

2  64 

4  77 

25  98 

2  610 

Average  . 

54.94 

6.65 

16.58 

2.18 

5.14 

24.38 

2  551 

APPENDIX  TABLE  3. — NITROGEN  BALANCES  OF  SHEEP  IN 

METALBOLISM  PERIODS  OF  MAINTENANCE  EXPERIMENT 

(The  figures  refer  to  the  entire  collection  period  of  7  days) 


Sheep 
No. 

Nitrogen 
in  alfalfa  hay 
consumed 

Nitrogen  in 
feces 

Nitrogen  in 
urine 

Nitrogen 
balance 

142... 

grams 
151 

grams 
49 

grams 
95 

grams 

+7 

143  

151 

48 

99 

44 

144  

151 

49 

93 

+9 

145.  .  . 

156 

49 

110 

—3 

146 
147  

156 
156 

50 
49 

99 
102 

+7 
-j-5 

148... 

159 

57 

100 

+2 

149  

159 

51 

110 

—  2 

150  

159 

55 

104 

o 

151.. 

147 

47 

96 

+4 

152  

147 

49 

92 

+6 

153  

147 

49 

84 

+14 

Average  

153 

50 

99 

+4 

UNIVERSITY  OF  ILLINOIS-URBAN* 


